A state of emergency is being imposed in the city of Khabarovsk in Russia's far east, as a toxic spill heads towards the Amur River from China.

A senior Russian official told the BBC that the mains supply of drinking water - taken from the Amur - would be cut off for several days.

A communications hotline has been set up between Chinese and Russian experts to monitor the benzene spill.

The city of Harbin in north-eastern China is relying on bottled water.

Khabarovsk is home to about 650,000 people and the authorities fear 1.5 million people in and around the city will be affected by the pollution.

Oleg Mitvol, deputy head of the Russian environmental monitoring agency Rosprirodnadzor, told the BBC that in Khabarovsk "the water supply will be shut off, because the purifying equipment cannot deal with benzene".

He said heating would not be affected but tap water would be cut for a few days and fish from the Amur would also be contaminated.

HARBIN TIMELINE

13 November Explosion at petrochemical plant, Jilin city

21 Nov Water to Harbin city cut off; local government cites mains maintenance

22 Nov State media say water could have been contaminated after the blast

23 Nov Authorities admit very high levels of benzene have been found in the water